Digital Magnetic Compass Gyroscopic Compensation
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Solution Overview
Problem
Existing electronic magnetic compasses face challenges in accurately determining magnetic north due to interference from ferromagnetic and electromagnetic objects, especially in handheld devices with compact designs and strong magnetic influences, leading to inaccurate user guidance during compensation procedures.
Innovation Solution
A method utilizing a three-axis magnetic field sensor, accelerometer, and gyroscope to provide user guidance for orienting the device into predetermined orientations, allowing for compensation of magnetic field deviations and determination of magnetic north, even in harsh conditions, by calculating compensation data and correcting for gyro drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If magnetic compensation is performed using only magnetic sensor data, then the compensation procedure can be simple, but the guidance becomes unreliable under severe magnetic disturbances
Solution Approach 1:
The gyroscope serves as an intermediary device that provides alternative azimuth information when magnetic sensors are unreliable. During compensation procedures, the gyroscope data mediates the guidance process, allowing the system to maintain reliability by switching between magnetic and gyro-based guidance depending on environmental conditions.
2Volume of moving object
If handheld devices use compact designs with strong magnetic components, then the device size is reduced, but magnetic interference with the compass increases
Solution Approach 1:
The patent replaces reliance on magnetic field measurements with gyroscopic measurements for azimuth determination. The gyroscope, being a mechanical inertial sensor rather than a magnetic sensor, is immune to ferromagnetic and electromagnetic interference, allowing compact device design with strong magnetic components without compromising compass functionality.
3Measurement precision
If magnetic sensors are used for azimuth determination, then the compass can provide north reference, but the measurements are falsified by magnetic objects
Solution Approach 1:
The patent extracts the azimuth determination function from the magnetic sensing system and relocates it to the gyroscopic system. By separating the north-reference function (still provided by magnetic sensors when applicable) from the azimuth measurement function (provided by gyroscope), the system eliminates the harmful effect of magnetic distortion on azimuth determination.
4Reliability
If gyroscope data is used for user guidance during compensation, then reliable azimuth information is available under all conditions, but the system complexity increases
Solution Approach 1:
The gyroscope is integrated into the device with dual functionality: it serves both as a user guidance tool during compensation procedures and as the primary azimuth determination sensor under severe magnetic interference. This multi-functionality justifies the added complexity by providing universal azimuth information capability across all operating conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables reliable azimuth information and effective magnetic field compensation with high accuracy (below 0.5°) in handheld devices, ensuring the compass function remains operational despite severe magnetic disturbances, and can be retrofitted or integrated into existing modules.
Implementation Method 1
determining a magnetic north reference based on magnetic field components sensed by a three-axis magnetic field sensor
Implementation Method 2
determining a level plane based on gravitational acceleration components sensed by an accelerometer
Implementation Method 3
providing user guidance for subsequently orienting the device into a predetermined desired range of orientation based on rotary rate components sensed by a gyroscope
Data Source
AI summary
The invention relates to a method for a field compensation of an electronic compass for influences to a geomagnetic field by magnetic objects in the vicinity of the compass, that is done with acquiring a magnetic field value by a magnetic field sensor and acquiring an inclination with respect to level plane by an accelerometer, in a discrete set of multiple orientations of the compass.Therein, a user guidance for subsequently orienting the compass into a predetermined desired range of orientation is provided to the user. In the following, compensation data are calculated from those magnetic sensor acquisitions to compensate for the influences in such a way, that a magnetic north heading is determinable based on the compensated magnetic field values.Therein, the user guidance for the compensation is done with a gathering of directional information based on rotary rate readings from a gyroscope for an azimuthal component of the orientation.